Lowrance electronic LMS-339cDF iGPS GPS Receiver User Manual


 
16
Align transducer centerline with hull bottom. A dual frequency
transducer (left) and a single frequency transducer (right).
How low should you go?
For most situations, you should install your Skimmer transducer so
that its centerline is level with the bottom of the boat hull. This will
usually give you the best combination of smooth water flow and protec-
tion from bangs and bumps.
However, there are times when you may need to adjust the transducer
slightly higher or lower. (The slots in the mounting brackets allow you
to loosen the screws and slide the transducer up or down.) If you fre-
quently lose bottom signal lock while running at high speed, the trans-
ducer may be coming out of the water as you cross waves or wakes.
Move the transducer a little lower to help prevent this.
If you cruise or fish around lots of structure and cover, your transducer
may be frequently kicking up from object strikes. If you want, you may
move the transducer a little higher for more protection.
There are two extremes you should avoid. Never let the edge of the
mounting bracket extend below the bottom of the hull. Never let the
bottom – the face – of the transducer rise above the bottom of the hull.
Shoot-Thru-Hull vs. Transom Mounting
In a shoot-thru-hull installation, the transducer is bonded to the inside
of the hull with epoxy. The sonar "ping" signal passes through the hull
and into the water. This differs from a bolt-thru-hull installation (often
called "thru-hull"). In that case, a hole is cut in the hull and a specially
designed transducer is mounted through the hull with a threaded shaft
and nut. This puts the transducer in contact with the water.
Typically, shoot-thru-hull installations give excellent high speed opera-
tion and good to excellent depth capability. There is no possibility of
transducer damage from floating objects, as there is with a transom-
mounted transducer. A transducer mounted inside the hull can't be
Transom
Tra
n
som
Hull bottom
Hull bottom
Transducer
centerline